Measuring apparatus and method

ABSTRACT

A method and apparatus is provided for determining a measurement of a portion of a load in a basket that is rotatably supported provided, the method includes: a) determining, a dry load measurement; b) spinning, the basket that is rotatably supported in order to gradually remove the liquid from the load, wherein the liquid is removed substantially by centrifugal force on the basket that is rotatably supported; c) determining a wet load measurement, wherein the dry load measurement is less than the wet load measurement; d) comparing the dry load measurement to the wet load measurement to determine a remaining liquid measurement; and e) repeating c) and d) until the remaining liquid measurement substantially is within a predetermined percentage threshold of about 0 percent to about 50 percent of the wet load measurement.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 11/929,546, filed Oct. 30, 2007, and entitled “MeasuringApparatus and Method” the entire contents of which is incorporatedherein to the extent necessary to practice the present invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure is related to measuring an aspect of a loadsupported by a container. More particularly, the present disclosure isrelated to measuring a size of a load in a tub or basket that is subjectto a rotational acceleration.

2. Description of Related Art

Vertical axis washing machines, also known as top loading washingmachines, represent a large portion of the overall washing machineconsumer market in the United States. Horizontal axis washing machinesrepresent a smaller segment of the United State market and abroadtypically represent a larger portion of the overall washing machineconsumer market.

Most vertical axis washing machines include a spin cycle for removingwater and/or detergents from the laundry using centrifugal force andspinning a wash load tub, also referred to as a laundry tub (“tub”) orbasket. During a typical spin cycle, the motor, typically an inductionmotor, of the washing machine spins the tub at relatively high speed(s).

Historically induction motors used in washers have been single phaseinduction motors or PSC induction motors. More recently 3-phaseinduction motors, have been used in some commercially available washers.The 3-phase motors in washers for home use are typically powered bystandard single phase AC household electric power. As part of a 3-phaseinduction motor washing machine, a circuit associated with the motorconverts the single phase AC household electric power to three phasepower; the three phase power is better at motor starting and operatesmore efficiently than single phase power.

A simplified explanation of an induction motor, ignoring losses follows:The induction motor has a rotor with a short-circuited winding inside astator with a rotating magnetic field. The flux from the rotating fieldinduces a current flow in the rotor. The frequency of the currentflowing is equal to the difference between the rotational speed of thestator field and the rotational speed of the rotor. This difference inspeed, or frequency, of the stator magnetic field and the rotor magneticfield is known as the slip.

The rotor current causes a rotor magnetic field, which is spinningrelative to the rotor at the slip frequency and relative to the statorfield, at the same slip frequency. The interaction between rotormagnetic field and the stator magnetic field generates a torque in therotor.

A washing machine wash cycle has various modes such as fill, drain andspin, agitation, and spin. Load sensing can occur before, during orafter various segments of the wash cycle. The weight of a load ofclothes loaded into a clothes washer for washing is an importantparameter in determining the proper amount of water and detergent to beused for the wash cycle. Large clothes loads require larger quantitiesof water than do small loads. Better clothes washability and significantwater and energy savings can be achieved when the proper amount of wateris filled into the washer tub for a given clothes load. Too much wateror detergent is wasteful, and too little of either will generallyadversely affect the effectiveness of the washing, and may result inincreased energy consumption due to a higher load on the motor as aresult of the inability of the clothes to move freely in the water.Additionally, load size may aid in determination of max spin speed anddegree of load imbalance. For example, a 1 lb. load with 0.5 lb.imbalance may be more severe than a 10 lb. load with 0.5 lb. imbalance.

Knowing the amounts of water and detergent used in the wash cycle can behelpful in providing an efficiently run washing machine. Spin cyclestypically run for a pre-determined amount of time based on very genericinformation such as the user selected load size. Because the load sizeis generically selected and is not based upon an actual load size, thewasher spin cycle can run for more (or less) time than is needed toextract liquid such as water or water mixed with detergent from theload, which consumes more energy than needed, causes greater wear on theload, takes more time to perform and is less effective at extraction.

Techniques or methods of estimation of the load of clothes loaded into awasher employed by the washer itself are desirable in that it eliminatesguesswork on the part of the machine operator which can lead to improperwater fill or use of an improper amount of detergent and improper spintime for appropriate liquid extraction. Knowing load size can alsoprevent damage to the washer by limiting max speed and prevent wear onthe load by limiting the amount of agitation performed. Prior arttechniques include displacement sensors mounted at tub springs; magnetand coil pickup sensing relative displacement of tub from chassis; andultrasonic transducers. Prior art washing machines that use sensinghardware are costly due to the need for dedicated sensing hardware.

Accordingly, there is a need for a washing machine that overcomes,alleviates, and/or mitigates one or more of the aforementioned and otherdeleterious effects of prior art washing machines.

BRIEF SUMMARY OF THE INVENTION

A washing machine is provided that includes measuring a load in a washerwith a motor. In one embodiment, an exemplary method of the presentinvention provides for a method of measurement, the method is furtherdescribed as a method of determining a measurement of a portion of aload in a basket that is rotatably supported where the basket that isrotatably supported defines at least one aperture. The method includesa) determining, at a first time, a dry load measurement; b) spinning, ata time after the first time, the basket that is rotatably supported inorder to gradually remove the liquid from the load, wherein the liquidis removed substantially by centrifugal force on the basket that isrotatably supported and wherein liquid exits the basket that isrotatably supported, through the at least one aperture of the isrotatably supported basket; c) determining at a second time, a wet loadmeasurement, wherein the dry load measurement is less than the wet loadmeasurement; d) comparing the dry load measurement to the wet loadmeasurement to determine a remaining liquid measurement; and e)repeating c) and d) until the remaining liquid measurement substantiallyis within a predetermined percentage threshold of about 0 percent toabout 50 percent of the wet load measurement.

In another embodiment, an exemplary apparatus of the present inventionincludes a washer comprising: a tub having a load therein and the tubbeing configured to receive a liquid therein and to remove the liquidtherefrom; and a control circuit configured to execute a loadmeasurement formula used to determine a measurement of the load with andwithout the liquid in the tub; wherein a dry load measurement withoutthe liquid and a wet load measurement with the liquid are taken at firstand second times, respectively, are used to determine a remaining liquidmeasurement, and wherein the wet load measurement is thereafter repeatedas liquid is removed from the tub and additional remaining liquidmeasurements are carried out based on the repeated wet load measurementsuntil the remaining liquid measurement substantially is within apredetermined range of between about 0 percent to about 50 percent ofthe wet load measurement.

Another exemplary embodiment of the present invention includes: Acomputer program product comprising: a program storage device readableby a circuit interrupter, tangibly embodying a program of instructionsexecutable by the circuit interrupter to perform method of determining ameasurement of a portion of a load in a basket that is rotatablysupported where the basket that is rotatably supported defines at leastone aperture, the method including: a) determining, at a first time, adry load measurement; b) spinning, at a time after the first time, thebasket that is rotatably supported in order to gradually remove theliquid from the load, wherein the liquid is removed substantially bycentrifugal force on the basket that is rotatably supported and whereinliquid exits the basket that is rotatably supported, through the atleast one aperture of the is rotatably supported basket; c) determiningat a second time, a wet load measurement, wherein the dry loadmeasurement is less than the wet load measurement; d) comparing the dryload measurement to the wet load measurement to determine a remainingliquid measurement; and e) repeating c) and d) until the remainingliquid measurement substantially is within a predetermined percentagethreshold of about 0 percent to about 50 percent of the wet loadmeasurement.

The above brief description sets forth rather broadly the more importantfeatures of the present invention in order that the detailed descriptionthereof that follows may be better understood, and in order that thepresent contributions to the art may be better appreciated. There are,of course, additional features of the invention that will be describedhereinafter and which will be for the subject matter of the claimsappended hereto.

In this respect, before explaining several embodiments of the inventionin detail, it is understood that the invention is not limited in itsapplication to the details of the construction and to the arrangementsof the components set forth in the following description or illustratedin the drawings. The invention is capable of other embodiments and ofbeing practiced and carried out in various ways. Also, it is to beunderstood, that the phraseology and terminology employed herein are forthe purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which disclosure is based, may readily be utilized as a basis fordesigning other structures, methods, and systems for carrying out theseveral purposes of the present invention. It is important, therefore,that the claims be regarded as including such equivalent constructionsinsofar as they do not depart from the spirit and scope of the presentinvention.

Further, the purpose of the foregoing Abstract is to enable the U.S.Patent and Trademark Office and the public generally, and especially thescientists, engineers and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. Accordingly, the Abstract is neither intended to definethe invention or the application, which only is measured by the claims,nor is it intended to be limiting as to the scope of the invention inany way.

Further, the purpose of the foregoing Paragraph Titles used in both thebackground and the detailed description is to enable the U.S. Patent andTrademark Office and the public generally, and especially thescientists, engineers and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. Accordingly, the Paragraph Titles are neither intendedto define the invention or the application, which only is measured bythe claims, nor are they intended to be limiting as to the scope of theinvention in any way.

The above-described and other features and advantages of the presentdisclosure will be appreciated and understood by those skilled in theart from the following detailed description, drawings, and appendedclaims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a sectional view of a vertical axis washing machine accordingto an exemplary embodiment of the present invention;

FIG. 2 illustrates a cross sectional view of various elements of theexemplary horizontal axis washer of the present invention;

FIG. 3 illustrates a side view of the exemplary washer of the presentinvention along lines 2-2 of the cross sectional view of FIG. 2;

FIG. 4 illustrates a functional block diagram of an exemplary embodimentof the washer of the present invention;

FIG. 5 a,b illustrates an exemplary method of the present invention;

FIG. 5 c illustrates another exemplary method of the present invention;

FIG. 6 is a graph of voltage vs. time, illustrating frequency andamplitude of an input voltage to the washer motor;

FIG. 7 a is a graph of speed vs. time, illustrating frequency andamplitude of an input voltage to the washer motor, where a positivefrequency jump occurs at t₁;

FIG. 7 b is a graph of speed vs. time, illustrating frequency andamplitude of an input voltage to the washer motor, where a negativefrequency jump occurs at t₁;

FIG. 8 illustrates a graph of load size vs. time and a line L plotted onthe graph and substantially fitted to the equation for a line and alsorepresentative of an equation for load size for an exemplary washer ofan embodiment of the present invention;

FIG. 9 illustrates an exemplary graph of load size vs. time including atheoretical load size plot representative of load variation over timefor an exemplary embodiment of the present invention.

FIG. 10 is a flowchart illustrating an exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION Washing Machine Introduction

Referring to the drawings and in particular to FIG. 1, a washing machine(“washer”) according to an exemplary embodiment of the present inventionis illustrated and is generally referred to by reference numeral 10. Forpurposes of clarity, aspects of washer 10 necessary for understanding ofthe present disclosure, as well as aspects helpful in understanding theoperation of washer 10 are described herein. Washer 10 described hereincan be a vertical axis washer 10 as is illustrated in FIG. 1 or ahorizontal axis washer 10, as is illustrated in FIGS. 2 and 3. One ofordinary skill in the art can perform the exemplary embodiments of theinvention described herein using either configuration. Like referencenumerals are used in the horizontal and vertical axis washerillustrations.

Washer 10 includes a motor 12 and a motor control unit 14. Motor 12 is athree-phase alternating current (AC) induction motor and, in someembodiments includes motor control unit 14 integral therewith. The motorcontrol, integral therewith is referred to herein as integrated controland motor (ICM) or control circuitry. Motor control unit 14 can includecircuitry customized for an exemplary embodiment of the presentinvention. Alternately a motor control circuit that is suppliedindependently of the motor could be used as can be determined by one ofordinary skill in the art. For purposes of illustration, the independentcontrol circuit 14 is in the same block diagram configuration as theintegrated motor control circuit 14 and therefore, not separatelyillustrated. The washer 10 is provided with input power such as singlephase AC power input 48, illustrated in FIG. 4.

Washer 10 includes an outer housing or cabinet 20 supporting a fixed tub22, a basket or moving tub (“tub”) 25, an agitator 26, motor 12, andmotor control unit 14 in a known manner. Agitator and basket driveshafts 30, 32 are also illustrated. Basket 25 is configured to holdarticles (not shown) such as clothes to be washed. Circuit 14 isconfigured so that it causes the circuit 14 to control the motor in amanner that results in determination of load size (load not shown). Thecontrol circuit includes a counter C and memory 56 for storage of loadsize data and other appropriate data as may be determined by one ofordinary skill in the art.

During a spin cycle, basket 25 and agitator 26 are configured to bedriven by motor 12 via motor drive shaft coupled to drive belt 29 torotate at a high speed about axis 28. In this manner, liquid within thearticles is removed by the centrifugal force imparted by the spin cycleand is allowed to exit the basket through openings (not shown). However,during a washing cycle, agitator 26 is configured to be driven by motor12 to rotate back-and-forth about axis 28 so that the clothes in thebasket are agitated. For example, agitator 26 is secured to an agitatordrive shaft 30 and basket 25 is secured to a basket drive shaft 32.Motor 12 is coupled to mode shifter 16 by a transmission 34. In thevertical washer configuration of FIG. 1, transmission 34 is configuredto transmit rotary motion imparted on a motor shaft 36 by motor 12 tomode shifter 16 via drive belt 29. In the horizontal washerconfiguration of FIG. 2, a direct belt drive is configured to transmitrotary motion imparted on a motor shaft 36 by motor 12 to tub 25 viadrive belt 29. FIG. 3 illustrates a side view of the exemplary washer ofthe present invention along lines 2-2 of the cross sectional view ofFIG. 2.

During a spin cycle, basket 25 and agitator 26 are configured to bedriven by motor 12 to rotate at a high speed about axis 28. In thismanner, liquid within the articles is removed by the centrifugal forceimparted by the spin cycle and is allowed to exit the basket throughopenings (not shown). During the spin cycle, basket 25 has an inertialload comprising the inertial load from the articles and inertial loadinherent to the basket 25. During spin cycle articles or clothingbecomes plastered to the wall of basket 25 at a first speed or plasterspeed. Plaster refers to the centrifugal force of the spin cycle pushingthe clothing against the wall or structure of the basket. The clothesremain positioned by centrifugal force during a time period the firstspeed or plaster speed to a second speed or maximum speed of thespinning basket. The plastered speed and maximum speed can be determinedby one of ordinary skill in the art.

Load Detection and Liquid Measurement

The exemplary electronic control circuits of the present inventioninclude components such as a microprocessor 61 (see FIG. 4) that can beprogrammed using a programming language such as C, C++ or assemblylanguage. Alternately the microprocessor could be an applicationspecific integrated circuit (ASIC). The type of microprocessor used inthe control circuit could be determined by one of ordinary skill in theart.

Another component illustrated in the examples of the present inventionis an AC to DC converter component 62 for converting single phase inputpower, such as conventional residential voltage of 110v, 60 Hz in theUS, to DC voltage. Additionally, there is a microprocessor 61 whichdrives the power stage 64 (inverter) appropriately to convert the DCvoltage into 3-phase AC, typically by pulse-width modulation (PWM). Thechoice of components in the power stage can be determined by one ofordinary skill in the art. For example, the power stage could compriseIGBTs (not shown) and Gate Drivers (not shown). The output of exemplaryinverter 64 is 3-phase voltage labeled phases U, V and W. One ofordinary skill in the art would be familiar with the U, V and W phasenomenclature, while others may be familiar with typical/similar phase A,phase B and phase C nomenclature (not shown). Phases U, V and W areillustrated in FIG. 4. The output voltage of the inverter 64 is inputvoltage 57 to the 3-phase induction motor 12 that is the exemplary motorfor the embodiments of the invention described herein.

Closed Loop Technique. The closed loop motor control circuitconfiguration uses available feedback including motor speed and DC bus(aka bulk) voltage 55. The control circuit 14 adjusts output frequencyand amplitude of voltage 57 to the motor 12 to achieve and maintain adesired speed level. The exemplary closed loop motor control circuitconfiguration of the present invention is used to provide washingmachine 10 load size determination. An exemplary closed loop controlcircuit of the present invention is illustrated in FIG. 4.

In FIG. 4 the exemplary closed loop motor control circuit 14 of thepresent invention performs washer 10 load detection by adjustinginverter 64 output frequency and amplitude of voltage 57 (also known asmotor input frequency and amplitude of voltage 57) to the motor 12. Thecontrol circuit outputs a signal to the inverter; the signal causes theinverter to adjust the frequency and amplitude of voltage to the motor12. The control circuit is important to adjusting inverter output. In anexemplary embodiment of the present invention, the drive system is anIntegrated Control 14 and Motor 12 (ICM). However, in other exemplaryembodiments of the present invention a motor and separate controlcircuit may be used in place of the ICM as may be determined by one ofordinary skill in the art. One of ordinary skill in the art wouldunderstand that other parameters (for example current or torque) couldbe used to drive the motor.

Plastering of articles or clothing (not shown) to the drum is aprerequisite to the calculations and/or measurements of an exemplaryembodiment of the present invention. Plastering is important because theload substantially stops moving within and relative to the drum. Thisallows the mechanical speed to stabilize and readies the load for thecalculations and/or measurements performed in the exemplary embodimentof the present invention.

A decrease in amplitude of the input voltage to the motorV_(input−motor) causes a decrease in torque and hence an increase in thetime Δt it takes to reach a target speed S_(motor). Further decreases inamplitude of the input voltage to the motor V_(input−motor) results ingreater time increments Δt for reaching target speed S_(motor). Thus,decreasing the amplitude of the input voltage to the motor allows formore accurate determination of load size due to a greater timedifferential V_(input−motor). The decrease in amplitude of the inputvoltage to the motor V_(input−motor) results in improved accuracy inload size determination to the extent that the amplitude is decreased toa magnitude at which the motor can continue to drive the load to thedesired speed. This is the lower limit or minimum predetermined valuefor input voltage to the motor V_(input−motor). Sufficient torque,provided by input voltage to the motor V_(input−motor) of at least theminimum predetermined value to drive the load to a desired speed isrequired to obtain, t₂, time at which the motor reaches the second motorspeed. At an input voltage to the motor V_(input−motor) that is lessthan the predetermined value, the motor would not accelerate due to lackof sufficient torque and therefore, the equation that is used to solvefor load size would be missing a variable, t₂, time at which the motorreaches the second motor speed. Hence, solving for load size under suchcircumstances would not be possible since the second motor speed is notreached in the absence of sufficient torque. It should be noted thatthere is another limit on the input voltage to the motorV_(input−motor), an upper limit or a maximum predetermined value, whichprevents over current to the control.

FIG. 8 illustrates a graph of load size vs. time and a line L plotted onthe graph and substantially fitted to the equation for a line/load sizefor an exemplary washer of an embodiment of the present invention. Loadsize can be calculated using the equation for a line y=m*x+b, whichcorresponds to the line L of the graph of FIG. 8 where time is plottedon the x-axis and load size is plotted on the y-axis. The equation for aline represents various exemplary washer 10 values as follows: y is theload size, m is the slope of the line, and b is the y intercept of theline. In using the equation for a line in the load size calculationperformed herein, it should be noted that two exemplary y values areassociated with the calculation. The first y value is y_(known) and isused to determine the constants m and b associated with a particularwasher 10. The second, y_(calculated), is used to determine load size inthe method of the present invention, using the previously solved forconstants m and b and time determined during performance of theexemplary method of the preset invention. Both y values y_(known) andy_(calculated) will be further explained below.

In the equation for a line in the load size calculation, y_(calculated),the slope m and the y-intercept b are constants that can be determinedby one of ordinary skill in the art, for example, through the use ofempirical data and a known load size (known) or y_(known) for a washer10. If we assume that m and b are constants and that we know the loadsize and the time to reach a desired speed, we are left with thefollowing equation which defines the line L of the graph of FIG. 8:

y _(known) =m*x+b  (4)

In order to solve for load size y_(calculated), the time x (alsorepresented as Δt) is determined, as well as a Resolution Factor

$\frac{y}{x} = \frac{\Delta \; y}{\Delta \; t}$

which is obtained from the line equation, as can be seen from the graphof FIG. 8 also representing the slope m of line L and empirical data andcan also be represented as

$\frac{y_{known}}{\Delta \; t}$

or

$\frac{{loadsize}\mspace{14mu} ({known})}{\Delta \; t}.$

Resolution Factor can be expressed as follows using the empirical datafrom TABLE A:

$\begin{matrix}{{{Resolution}\mspace{14mu} {Factor}} = {\frac{y}{x} = {\frac{y_{known}}{\Delta \; t} = \frac{{load}\mspace{14mu} {size}\mspace{14mu} ({known})}{\Delta \; t}}}} & (5)\end{matrix}$

where Δt=t₂−t₁, and t₁ and t₂ correspond to S_(motor 1) and S_(motor 2)of the exemplary method of FIG. 5 a, b, respectively.

Empirical data of TABLE A for an exemplary washer 10 provides the weightand time measurements used in the exemplary calculations herein.

TABLE A LOAD WEIGHT lbs AVERAGE TIME ms 0 621 19.136 1392

Using the Line Equation L, and solving for m, the slope of the line, andalso the resolution factor

$\frac{{load}\mspace{14mu} {size}\mspace{14mu} ({known})}{\Delta \; t},$

provides values for a specific calculated load size y_(calculated)equation for the washer 10. Note that the equation is specific to themotor configuration of the washer 10. For example, empirical data for anexemplary washer 10 provides weight and time measurements of TABLE A.Other calculated load size y_(calculated) equations for other washerscould be formulated by one of ordinary skill in the art.

Using empirical data to solve for the slope m where:

$\begin{matrix}{m = {\frac{\Delta \; y}{\Delta \; x} = {\frac{\Delta \; {weight}}{\Delta \; t} = {\frac{19.136 - 0}{1392 - 621} = 0.02484}}}} & (6)\end{matrix}$

Next, solve for b (also known mathematically as the y-intercept) usingΔx, y and m where:

b=y _(known)−(m*Δx)=19.136 lbs−(0.02484 lbs/ms*1392 ms)=−15.44 lbs  (7)

By using the calculated Resolution Factor of equation (5), and knowntimes Δt=t₂−t₁, the load size can be determined as follows:

Load size(calculated)=y _(calculated) =Δt*(resolution factor)+b  (8)

The equation for calculated load size equation for exemplary washer 10,solved for above, is:

Load Size(calculated)=0.02484 lbs/ms*Δt(ms)−15.44 lbs  (9)

With the load size equation determined for washer 10, and a time valueΔt, typically measured in milliseconds (ms) obtained in the execution ofthe exemplary method of the present invention, Load Size(calculated) ory_(calculated) can be calculated using the exemplary method of thepresent invention and spherical data determined using the method.

The load constants include resolution factor and y-intercept for awasher 10; the load constants are either a predetermined value in theICM, or are be provided from the control circuitry of the washer 10. Theload constants, resolution factor and y-intercept, are calculated fromthe same data set and both change with changes to the data set. Notethat if the resolution factor is decreased then the measurableresolution of load detection algorithm is increased. The load constantsare used during washer 10 cycles to determine load size which isimportant with the present variable measurement washers, includingvariable load size, so that load measurement can be tuned to the washersetting, e.g. washer model, fabric type, user selected load size, etc inorder to determine the amount of water, agitation, detergent or othersetting or inputs for proper washing. These washer settings may bedetermined by one of ordinary skill in the art.

It should be noted that a stable motor speed is important to the methodof the present invention. Motor speed S_(motor) can be calculated as afunction of electrical frequency or the frequency of the voltage to themotor ƒ_(input) and a number of motor poles for the motor of the washer10. The following equations are used to model the relationship betweenfrequency and motor speed and therefore the speed of the washing machinetub 25 which is driven by the motor:

$\begin{matrix}{S_{motor} = {\frac{120*f_{input}}{\# \mspace{14mu} {motorpoles}}\mspace{14mu} \left( {{Motor}\mspace{14mu} {Speed}\mspace{14mu} {Equation}} \right)}} & (10)\end{matrix}$

To move from a first motor speed S_(motor 1) to a second motor speedS_(motor 2), the frequency of the voltage to the motor ƒ_(input) isadjusted. Amplitude of the input voltage signal may also be adjusted tothe extent that it can provide the desired motor torque.

In the following example, Y is used to represent amplitude of voltage; Ycorresponds, for example, to the Y-axis of FIG. 6. Furthermore,exemplary electrical frequency or frequency of motor input voltage isrepresented by ƒ. An exemplary control scheme of the present inventionsubstantially instantaneously adjusts electrical frequency ƒ (andoptionally amplitude Y) of input (electrical frequency) 58 to thewashing machine induction motor 12 in order to obtain a time incrementfor the mechanical frequency (measured speed w) to equal the amplitudeof the electrical frequency ƒ is made while being cautious that theincrement does not result in high currents. The voltage adjustment ofamplitude Y may be required to prevent high currents, or desired toincrease resolution. Too great of an amplitude or frequency adjustmentto motor input voltage 58 can result in high currents that could damagethe gate driver or IGBTs or motor through thermal overheating. Theexemplary method of the present invention determines a measured timeincrement in order to obtain a load size from a predetermined load sizeformula and the measured time increment. The control circuit 14 isprocessing a feedback signal during the initial period wherein the loadis plastered. The control circuit is not processing a feedback signalduring a period wherein the time is measured. The operation of thecontrol circuit 14 in open loop mode can be performed by one of ordinaryskill in the art by for example, physically switching open the feedbackloop, or disabling the proportional integral (PI) control 63 of thecontrol circuit 14 of the Integrated Motor Control (ICM). Other suitablemanners of opening or closing the feedback control loop may bedetermined by one of ordinary skill in the art.

Induction motor 12 speed is determined using speed sensor 65 of theintegrated control 14. The motor 12 is connected to the integratedcontrol circuit 14 via the speed sensor 65. Feedback 52 is obtained bythe Integrated Control 14 from speed sensor 65, which can be, forexample, a hall sensor (not shown). The feedback 52 of rotor speed tothe processor 61 integrated control 14 is processed and output via3-phase microprocessor output 53 and provided to inverter 64 where it isapplied to the voltage at the inverter 64, so that voltage isappropriately adjusted for output and hence motor input voltage therebymotor speed and torque are adjusted during the closed loop operation ofplastering which is performed at a slow rate of acceleration so as tospread the load about the tub wall 24.

Returning now to the flowchart of FIG. 5 a,b, illustrating an exemplarymethod of the present invention, at operator 500, the method begins.Next at operator 501, increment counter C is initialized. Next atoperator 502 the motor 12 is driven using a closed loop control circuit14 until the initial motor speed S_(motor 0) is sufficient to plasterthe load. It should be noted that an assumption is made that the load isplastered at a speed S_(plastered); hence if S_(plastered) is reachedthen the clothes are assumed to be plastered. The closed loop is used sothat the motor 12 accelerates slowly and the slow centrifugal forcespreads out the articles or clothes (not shown) in the tub 25 in agenerally even manner. This continues until the clothes are plastered tothe wall 24 of the tub 25. At operator 504 a query is made as to whetherthe assumed plaster speed S_(plastered) has been achieved. If the answerto the query of 504 is NO, the query is repeated until the assumedplaster speed S_(plastered) is achieved and the answer to the query of504 is YES. During the time that is incremented while the speed isapproaching assumed plastered speed S_(plastered), the motor speed ismostly increasing and stabilizing as is illustrated in the graph of FIG.7 a along the X-axis between t₀ and t₁. FIG. 7 a is a graph of speed vs.time, illustrating frequency and amplitude of an input voltage to thewasher motor, where a positive frequency jump occurs at t₁. FIG. 7 b isa graph of speed vs. time, illustrating frequency and amplitude of aninput voltage to the washer motor, where a negative frequency jumpoccurs at t₁. Next at operator 506, operate feedback control circuit inopen loop configuration.

At operator 508, the control circuit operates to provide a firstpredetermined input voltage to the motor, the first predetermined inputvoltage to the motor having a first predetermined electrical frequencyX1 and a first predetermined amplitude Y1. It should be noted that inrepresenting predetermined amplitude and frequency, the operators X andY are used to identify frequency (and amplitude), respectively. In thisrepresentation, X and Y correspond to the X-axis and Y-axis for thegraph of an exemplary input voltage signal, such as the voltage graph ofFIG. 6 (voltage vs. time). The first predetermined frequency X1 andamplitude Y1 are chosen such that a graph of the load line (load sizevs. time) produces a well-defined line with a substantially gradualslope. Next, at operator 510 a query is made as to whether there is astable motor speed. If the answer to the query of 510 is NO, the queryis repeated until the motor speed is stable and the answer to the queryof 510 is YES. At operator 512 it is noted that after the motorstabilization of operator 510, the feedback control circuit remains inoperation in the open loop configuration.

Following operator 512, at operator 514, the control circuit operates toprovide a second predetermined input voltage to the motor, the secondpredetermined input voltage to the motor having a second predeterminedelectrical frequency X2 and a second predetermined amplitude Y2. Again,it is noted that in representing predetermined amplitude and frequency,the operators X and Y are used to identify frequency (and amplitude),respectively. In this representation, X and Y correspond to the X-axisand Y-axis for the graph of an exemplary input voltage signal, such asthe voltage graph of FIG. 6 (voltage vs. time). The second predeterminedfrequency X2 and amplitude Y2 are chosen such that a graph of the loadline (load size vs. time) produces a well-defined line with asubstantially gradual slope. A timer 51 (illustrated in FIG. 4) isstarted substantially upon application of the second predetermined inputvoltage, illustrated at operator 516. Next, at operator 518 a query ismade as to whether there is a stable motor speed. If the answer to thequery of 518 is NO, the query is repeated until the motor speed isstable and the answer to the query of 518 is YES. Next, at operator 520,the timer 51 is stopped and a time Δt=t₂−t₁ is determined; the time Δtis determined where the time values t₂ and t₁ obtained using timer 51,correspond to t₁ timer 51 start time and t₂ timer 51 stop time,respectively. Operator 522 follows and an elapsed time reading sum iscalculated as well as average elapsed time reading which uses theformula (11) as follows:

$\begin{matrix}{{{Average}\mspace{14mu} \Delta \; t} = {\overset{\_}{\Delta \; t} = \frac{{\sum\limits_{C}^{C + 1}t_{2}} - t_{1}}{C}}} & (11)\end{matrix}$

Where C is the increment counter initialized to 1 at operator 501 andincremented at operator 534.

Next, at operator 524, a query is made as to whether the operators 502through 522 should be repeated. If the answer to the query of operator524 is NO, then operator 526 follows operator 524, and a load size iscalculated based upon the average time determination of operator 522.The load calculation of operator 522 uses the load size equation for thespecific exemplary washer, for example, equation (9) where LoadSize(calculated )=0.02484 lbs/ms*Δt(ms)−15.44 lbs. The load sizeequation is predetermined and part of the control circuit 14. The Δtvalue determined using elapsed time from timer 51 is with the load sizeequation to solve for load size. After operator 526, the method ends atoperator 530.

One of ordinary skill in the art would understand that electricalsystems, such as, for example an integrated motor control system for ahorizontal axis washer, can be sensitive to environmental changes. Theseenvironmental changes introduce electrical noise and/or inefficienciesinto the control circuit. In an exemplary alternate embodiment of thepresent invention, a compensation for noise factors and inefficienciesis performed to provide additional accuracy in calculating the loadsize. For example, dc bus voltage, temperature and load imbalance canintroduce electrical noise and/or inefficiencies into the controlcircuit 14 for washer 10. In an alternate embodiment of the exemplarymethod of the present invention, illustrated with dashed lines atoperator 528 of FIG. 5 a,b, a compensation is performed for electricalnoise and/or other electrical inefficiencies. After operator 528,operator 526 follows and load size is calculated using the load sizeequation such as, for example, equation (8) above.

Inefficiencies can be introduced by the dc bus 55 voltage, which maychange substantially during a washer 10 cycle. The change in dc bus 55voltage may impact the peak energy provided to motor 12 windings (notshown) and introduce error into the load size calculations. The dc bus55 voltage is obtained, for example, using a potential transformercoupled to the dc bus 55 and input to an analog to digital (A/D)converter 66 of the microprocessor 61.

Another exemplary variable or noise, temperature of the motor 12, canintroduce error into the load size calculation For example, motors madewith aluminum windings have resistance that increases as the motorwindings temperature increases. A motor with aluminum windings runninghotter than room temperature may be running much less efficiently than amotor with aluminum windings running at room temperature. The inverter64 includes a temperature sensor that indicates the heat near theinverter 64, and may thus be used to represent an approximation of themotor 12 winding temperature. A temperature sensor (not shown) providesa temperature representative of motor winding temperature to themicroprocessor 61. One of ordinary skill in the art can determine whichvariable to use in compensating for noise and/or inefficiencies withrespect to temperature. In the present example, motor windingtemperature and/or heat proximate to the inverter 64 can be used. Theseexamples are not meant to limit the compensation; other variables can bedetermined by one of ordinary skill in the art.

A further exemplary variable or noise is a load that is out of balance(OOB), where the energy from the OOB or imbalance is transferred intoshock(s) to, or vibration of, the washer 10 that may cause inaccuracy inthe load size calculation. Various calculations may be performed todetermine the imbalance of the load in the washing machine basket or tub25. These calculations provide a basis for ensuring that the load sizecalculation is not improperly affected by such an imbalance condition.

In summary, to compensate for noise parameters a normalizationcalculation uses an average elapsed time reading i.e. the time it takesfor the rotating drum or moving tub 25 to change state, and applies theexemplary compensation calculation, explained in the exemplaryembodiment above, to decrease the impact of the noise variables on theload size calculation. The result is a compensated elapsed timemeasurement that can be used in the load size calculation, such as aload size calculation using equation (8) above. It should be noted thatwhile several exemplary noise factors such as electrical noise and/orinefficiencies are used for illustration purpose, other factors may beused as may be determined by one of ordinary skill in the art usingdesigned experiments and regression techniques.

Returning to the flow chart of FIG. 5 a,b and the query of operator 524,if the answer to the query of operator 524 is YES, then the methodcontinues, at operator 532 the control circuit is operated in closedloop configuration, and the increment counter C is incremented by 1 atoperator 534. Then operators 502 through 522 are repeated as describedabove.

In the exemplary embodiment of the present invention, motor 12 inputvoltage (frequency and amplitude) is adjusted such that motor 12 speedS_(motor) and torque T are likewise adjusted. The embodiment of theinvention is carried out as follows: Speed of the induction motor 12S_(motor) is measured at predetermined times i.e. t₁, t₂, or atpredetermined intervals of time i.e. t₂-t₁. At various intervals, afterload plastering, time t is measured and load size is calculated usingthe motor control circuit 14 and the specific load size equationprovided with the control circuit. The accuracy of the load sizecalculation is improved by operating the method multiple times (i.e.multiple iterations of the flow chart of FIG. 5 a,b) and averaging thecalculated load size. Additionally, resolution which corresponds to Δtis increased with greater time differences Δt.

Exemplary Resolution is seen in the following two calculations ofresolution factor from equation (5) above:

$\begin{matrix}{{{Resolution}\mspace{14mu} {Factor}} = {\frac{y}{x} = {\frac{y_{known}}{\Delta \; t} = \frac{{load}\mspace{14mu} {size}\mspace{14mu} ({known})}{\Delta \; t}}}} & (13)\end{matrix}$

For a 20 lb load, where t₂=750 ms and t₁=500 ms and the smallestmeasurable increment is 1 ms, the First Resolution Factor is:

Resolution Factor(1)=20/(750−500)=0.08 lbs/ms.  (14)

However, resolution can be increased where a greater time differentialis obtained. For a 20 lb load, where t₂=1500 ms and t₁=750 ms, theSecond Resolution Factor is:

Resolution factor(2)=20/(1500−750)=0.027 lbs/ms  (15)

Resolution Factor (2) allows the representation of load with 3 timesgreater resolution than Resolution Factor (1). It should be noted thatimproving resolution does not improve accuracy. With improvedresolution, there are more decimal places as a result of calculationsbut accuracy is not improved. Improving resolution increases the numberof load values that can be represented with the same inputs. Forexample, 0.08 lbs/ms allows us to represent 0 and 0.08 lbs. However,0.027 lbs/ms allows us to represent 0, 0.027, 0.054 and 0.081 lbs. Thenumbers in this example are for purposes of explanation and are notmeant to limit the load values or inputs to any particular numbers orany particular range of numbers. Values may be determined by one ofordinary skill in the art.

From the above calculations, it can be seen that the embodiment of thepresent invention avoids the use of dedicated weight sensors byquantifying time to reach stable speed and calculating load sizemultiple times to improve accuracy. Note that accuracy improves thecorrectness of the measurement but not the resolution in which thatmeasurement is represented. The calculation of load size multiple timesis illustrated in the flowchart of FIG. 5 a,b where operators 502through 522 are performed again if the answer to the query of operator524 is YES. The calculated load size determined from multiple operationsof the method of FIG. 5 a,b can be added together and averaged in orderto obtain a more accurate calculated load size. Empirical data for anexemplary embodiment of the present invention has lead to the conclusionthat three operations of the method of FIG. 5 a,b, for operators 502through 522 results in suitable accuracy. The three operations can beperformed, for example, through the use of an increment counter C ofoperator 501, and the repeat query 524 in the flowchart of FIG. 5 a,b;alternately other embodiments may be determined by one of ordinary skillin the art. Other embodiments of the present invention may call foradditional accuracy (more than 3 operations of the method steps) andadditional operations of the method of FIG. 5 a,b. The accuracy forother embodiments of the present invention can be determined by one ofordinary skill in the art. Hence, the three operations stated herein arenot meant to limit the invention and other numbers of operations aresuitable as determined by one of ordinary skill in the art.

FIG. 5 c illustrates another exemplary method of the present invention.The method of FIG. 5 c starts at 550 and includes 551, attain a speed atwhich the load is assumed to be plastered; 552, allow the speed tostabilize once the motor has reached the predefined speed (the speed atwhich the load is assumed to be plastered); 553, adjust the voltage suchthat an instantaneous frequency jump of the motor input voltage occurs(Note that the instantaneous frequency jump occurs in open loop modesince the nature of closed loop mode would prevent an instantaneousfrequency jump). Operator 554, elapsed time is measured frominstantaneous frequency jump until target speed is reached Next at 555,the load size is calculated using the measured elapsed time. At 556, aquery is made as to whether the method is repeated. If the answer to thequery is NO, then at 557 the method terminates. If the answer to thequery 556 is YES then the method is repeated starting at 551.

FIG. 9 illustrates an exemplary graph of load size vs. time including atheoretical load size plot representative of load variation over timefor an exemplary embodiment of the present invention. Note that FIG. 9illustrates that by determining changes in load size due to loss ofliquid, i.e. water, during spin, the spin cycle speeds and/or time maybe dynamically adjusted until the desired amount of water is extractedfrom the clothes. It should be noted that extraction of a liquid isgenerally discussed herein as water extraction; however, water is usedas an example and is not meant to limit the invention.

This invention provides a way to estimate the amount of water extractedfrom a load, such as a washing machine load, during a spin cycle byusing the load detection method discussed in the method of FIGS. 5 a,b,cabove including inverter 64 and motor 12 programming. The load detectionprocess may be performed in various ways using common motor feedbackdata, for example, speed, torque, current, and power factor, etc. Loadsize may also be detected by using sensors. Alternately load size may bemeasured using mechanical measuring device to measure weight i.e. atleast one strain gauge affixed to the washer as may be determined by oneof ordinary skill in the art. In an alternate embodiment the washercould be arranged with suitable measurement device 13 (shown in FIG. 3)such as a scale retrofitted to the shock absorbers (not shown) in awasher; one of ordinary skill in the art could determine what type ofmechanical device could be used for measurement in a washer.

The primary method of detecting load size for this invention uses speedfeedback discussed above with respect to FIG. 4 functional block diagramand FIGS. 5 a,b and 5 c flowcharts. FIG. 9 illustrates, in an exemplaryembodiment of the present invention, the points at which load size isdetermined and with which water amount in the load can be determined. Todetect the amount of extracted water, first, at t₁ of FIG. 9, the dryload size S₁=dry load size is calculated at the beginning of the washcycle. Then the wet load size S₂=wet load size is calculated, after thewash cycle (which can include, for example, an agitate phase) at t₂ ofFIG. 9, which is, for example, before the spin cycle.

Finally, during the spin cycle illustrated in FIG. 9, the present loadS₃,S₄,S₅ size is intermittently calculated (at t₃,t₄ ,t₅ ) and comparedwith the dry S₁ and wet load sizes S₂ (previously calculated at t₁,t₂,respectively) to determine the amount of water that has been extracted.Once a desired or predetermined amount of water is extracted, the spincycle is determined to be complete and the washer may be stopped.

Spin cycles typically run for a pre-determined amount of time based ongeneric information such as a user selected load size (i.e. small,medium, large). The exemplary embodiment of the present inventionprovides for dynamic adjustment of washer spin by detecting the amountof water that has been extracted at least one time point t₃,t₄ ,t₅ . Bydetermining change in load size due to loss of water during spin (i.e.S₂−(S_(3 l or S) ₄ or S₅)), the spin cycle speeds and/or time may bedynamically adjusted until a desired amount of water is extracted fromthe clothes.

FIG. 10 is a flowchart illustrating an exemplary embodiment of thepresent invention. At 100 the method begins. At 102 a dry load size S₁is measured. The Dry Load Size S₁ is determined at the beginning of thewash start, before water or liquid is added. Next, preparation symbol104 represents a wash cycle. At 106, spin is performed. It should benoted that dotted line 105 indicates a dynamic spin cycle is performed.The length of the spin cycle may be reduced by detecting when an amountof liquid remaining in the load falls below 50% of the total load orbelow a predetermined percentage threshold. The threshold may beadjusted based on load type, such as heavy or light loads, variousfabric type loads i.e. terry cloth, cotton or mixed fabric loads. At108, wet load size S_(n) is measured. At 110 percent residual water((S_(n)−S₁)/S_(n)) is determined. This determines a which portion of theload size is residual water as a percentage of the wet load size. To getthis percentage, divide the water load size by the total wet load size.The liquid load size and percent residual liquid are calculated usingequations such as the following:

Liquid Load Size=Wet Load Size−Dry Load Size  (16)

Percent Residual Liquid=Liquid Load Size/Wet Load Size  (17)

Returning to FIG. 10, next at 112 a query is made as to whether thepercent residual water is less than a predetermined percentagethreshold. If the answer to the query is NO, then the method returns to108 through 112 as previously described. If the answer to the query isYES, then the method proceeds to 114 and spin is stopped. Next at 116,the method ends.

Advantages of the present invention includes advantages in the exemplaryembodiments presented herein, including: 1) Spin cycle speed andduration may be dynamically adjusted based on amount of extracted water;2) special sensors may or may not be used, hence affording flexibility;3) re-use of data determined in a method described in FIGS. 5 a,b and cherein; 4) water extraction has increased effectiveness due tomeasurement during extraction; 6) washer cycle time is reduced; 7) powerconsumption can be reduced if water extraction time is reduced; 8) loadwear is reduced when water extraction time is reduced (i.e. less wear onclothes due to shorter spin times and/or lower spin speeds); and 9)increased marketability due to the benefits of the water extractionfeature.

The exemplary embodiments of the present invention implement methodsusing firmware and related hardware to determine changes in load size.The present invention is implemented herein in exemplary washers; one ofordinary skill in the art would recognize that the present inventioncould be implemented in other apparatus with rotational loads. Whilemotor speed is used herein to determine load size, determining waterextraction by measurement of load via any of the various electricalproperties of the washer motor 12 or drive can be performed by one ofordinary skill in the art using the present invention. The exemplaryembodiments of the present invention are implemented as at least onesoftware component in the inverter 64 and motor 12 of the washingmachine.

In addition to the accomplishment discussed above, this exemplaryembodiment of the present invention accomplishes load detection throughthe adjustment of output voltage from the control circuit or integratedmotor control so that the tub speed reaches various speeds and the timebetween speed increments is measured.

In addition to the accomplishment discussed above, this exemplaryembodiment of the present invention accomplishes load detection throughthe use of time measurement and speed feedback after applying asubstantially instantaneous frequency jump. The substantiallyinstantaneous frequency jump(s) described herein are frequency changeswherein the frequency change from the first input voltage to the secondinput voltage is substantially instantaneous negative or positivefrequency change. Note that while the use of speed feedback is discussedmore prevalently with regard to closed loop mode, even in open loopmode, speed feedback is used. In open loop mode speed feedback is usedto determine when the speed is stable; speed feedback is not used forspeed control in the embodiments of the invention described herein.However, the PI controller is disabled so the microprocessor 61 will notautomatically adjust the voltage input 58 to the motor 12. In open loopmode, the voltage amplitude and frequency are controlled manually. Inclosed loop mode, the voltage amplitude and frequency are automaticallycontrolled using a PI controller with speed error as the input.Measurements can be performed by the exemplary method of the presentinvention in a substantially instantaneous frequency jump when thecontrol circuit is operating in open loop mode.

Advantages to the embodiments of the present invention include that costis reduced because various, prior art components are not required.Additionally the exemplary method of the present invention can beperformed on a dry load or a wet load. Dedicated sensors are not used inthe exemplary embodiments of the present invention; time and speed aremeasured and/or calculated, hence there is a cost reduction in materialsper unit. The exemplary method of the present invention accomplishesload detection by transitioning between open and closed loop modes. Themethod also accomplishes the adjustment of constants “on the fly” orduring the operation of the washer so that load measurement is tuned towasher settings (e.g. fabric type, user selected load size, etc.).Resolution is enhanced by lowering torque and accuracy is enhanced byrepeating portions of the method multiple times. Calibrationfunctionality for a particular washer can be part of the method storedin the washer control circuit; hence calibration is “built in” to thewasher in some embodiments. The present invention can be performed inboth horizontal axis and vertical axis washers, as may be determined byone of ordinary skill in the art.

The aforementioned embodiments of the present invention use an exemplarymotor platform that is an AC induction motor. In an alternate embodimentof the present invention a different motor platform that is not an ACInduction motor may be used. One of ordinary skill in the art coulddetermine an appropriate motor platform for the present invention. Itshould be noted that the control circuit 14 could be a circuit otherthan a circuit of a commercially available integrated motor and control.

The exemplary inventions discussed herein accomplish load detection byelimination of components such as pressure switches or pressuretransducers, (for example, pressure switch coupled to the tub when thetub is still) and associated circuitry to determine load size and/or bythe use of an adaptive circuit that provides for consistent operation ofthe washing machine over varying frequency and amplitude electricalinput.

It should also be noted that the terms “first”, “second”, “third”,“upper”, “lower”, and the like may be used herein to modify variouselements. These modifiers do not imply a spatial, sequential, orhierarchical order to the modified elements unless specifically stated.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

1. A method of determining a measurement of a portion of a load in abasket that is rotatably supported where the basket that is rotatablysupported defines at least one aperture, the method comprising: a)determining, at a first time, a dry load measurement; b) spinning, at atime after the first time, the basket that is rotatably supported inorder to gradually remove the liquid from the load, wherein the liquidis removed substantially by centrifugal force on the basket that isrotatably supported and wherein liquid exits the basket that isrotatably supported, through the at least one aperture of the isrotatably supported basket; c) determining at a second time, a wet loadmeasurement, wherein the dry load measurement is less than the wet loadmeasurement and; d) comparing the dry load measurement to the wet loadmeasurement to determine a remaining liquid measurement; and e)repeating c) and d) until the remaining liquid measurement substantiallyis within a predetermined percentage threshold of about 0 percent toabout 50 percent of the wet load measurement.
 2. The method of claim 1wherein in e) the predetermined percentage threshold is dynamicallyconfigurable by a user based upon load type.
 3. The method of claim 1wherein the wet load measurement and dry load measurement made at thefirst time and the second time each comprise: a) accelerating the basketthat is rotatably supported to a stable rotational speed; b) measuring atime for the basket that is rotatably supported to reach the stablerotational speed; c) providing a load size equation comprising an inputsubstantially equal to a measured time that the basket that is rotatablysupported reaches the stable rotational speed; and d) determining a loadsize using the load size equation.
 4. The method of claim 1 wherein thewet load measurement and dry load measurement are made using amechanical measuring device operatively connected to the basket that isrotatably supported.
 5. A washer comprising: a tub having a load thereinand the tub being configured to receive a liquid therein and to removethe liquid therefrom; and a control circuit configured to execute a loadmeasurement formula used to determine a measurement of the load with andwithout the liquid in the tub; wherein a dry load measurement withoutthe liquid and a wet load measurement with the liquid are taken at firstand second times, respectively, are used to determine a remaining liquidmeasurement, and wherein the wet load measurement is thereafter repeatedas liquid is removed from the tub and additional remaining liquidmeasurements are carried out based on the repeated wet load measurementsuntil the remaining liquid measurement substantially is within apredetermined range of between about 0 percent to about 50 percent ofthe wet load measurement.
 6. The device of claim 5, wherein the tub isspinable and control circuit is further configured to control thespinning of the tub until the remaining liquid measurement is within thepredetermined range.
 7. A computer program product comprising: a programstorage device readable by a circuit interrupter, tangibly embodying aprogram of instructions executable by the circuit interrupter to performmethod of determining a measurement of a portion of a load in a basketthat is rotatably supported where the basket that is rotatably supporteddefines at least one aperture, the method comprising: one aperture, themethod comprising: a) determining, at a first time, a dry loadmeasurement; b) spinning, at a time after the first time, the basketthat is rotatably supported in order to gradually remove the liquid fromthe load, wherein the liquid is removed substantially by centrifugalforce on the basket that is rotatably supported and wherein liquid exitsthe basket that is rotatably supported, through the at least oneaperture of the is rotatably supported basket; c) determining at asecond time, a wet load measurement, wherein the dry load measurement isless than the wet load measurement and; d) comparing the dry loadmeasurement to the wet load measurement to determine a remaining liquidmeasurement; and e) repeating c) and d) until the remaining liquidmeasurement substantially is within a predetermined percentage thresholdof about 0 percent to about 50 percent of the wet load measurement.